The present invention relates to an aglucone isoflavone enriched vegetable flour and an aglucone isoflavone enriched vegetable grit, and methods for providing such by converting isoflavone glucosides in a vegetable material to aglucone isoflavones and processing the vegetable material into a vegetable flour or grit.
Isoflavones occur in a variety of leguminous plants, including vegetable protein materials such as soybeans. These compounds include daidzin, 6xe2x80x3-OAc daidzin 6xe2x80x3-OMal daidzin, daidzein, genistin, 6xe2x80x3-OAc genistin, 6xe2x80x3-OMal genistin, genistein, glycitin, 6xe2x80x3-OAc-glycitin, 6xe2x80x3-OMal glycitin, glycitein, biochanin A, formononentin, and coumestrol. Typically these compounds are associated with the inherent, bitter flavor of soybeans.
The isoflavones in vegetable protein materials include isoflavone glucosides (glucones) and aglucone isoflavones. Isoflavone glucosides have a glucose molecule attached to an isoflavone moiety. Additional moieties may be attached to the glucose molecule of an isoflavone glucoside, for example, 6xe2x80x3-OAc genistin contains an acetate group attached to the six position of the glucose molecule of genistin. Aglucone isoflavones consist solely of an isoflavone moiety.
Soy contains three xe2x80x9cfamiliesxe2x80x9d of isoflavone compounds having corresponding glucoside and aglucone members: the genistein family, the daidzein family, and the glycitein family. The genistein family includes the glucoside genistin, the conjugates 6xe2x80x3-OMal genistin (6xe2x80x3-malonate ester of genistin) and 6xe2x80x3-OAc genistin (6xe2x80x3-acetate ester of genistin); and the aglucone genistein. The daidzein family includes the glucoside daidzin, the conjugates 6xe2x80x3-OMal daidzin, and 6xe2x80x3-OAc daidzin; and the aglucone daidzein. The glycitein family includes the glucoside glycitin, the conjugate 6xe2x80x3-OMal glycitin, and the aglucone glycitein.
In the production of commercial products the focus has been to remove these materials. For example, in a conventional process for the production of a soy protein isolate or concentrate isoflavones in the protein are usually removed by exhaustive washing. The washes are typically discarded.
It has recently been recognized that the isoflavones contained in vegetable materials such as soybeans, clover, alfalfa, peanuts, and nearly all types of legumes have medicinal value. While all the isoflavones are of interest in medical evaluation, the aglucones are the specific isoflavones of most interest. Geinstein and daidzein may significantly reduce cardiovascular risk factors. xe2x80x9cPlant and Mammalian Estrogen Effects on Plasma Lipids of Female Monkeysxe2x80x9d, Circulation, vol. 90, p. 1259 (October 1994). Genistein and daidzein are also thought to reduce the symptoms of conditions caused by reduced or altered levels of endogenous estrogen in women, such as menopause or premenstrual syndrome, as disclosed in U.S. Pat. No 5,498,631. It has recently been recognized that aglucone isoflavones may inhibit the growth of human cancer cells, such as breast cancer cells and prostate cancer cells, as described in the following articles: xe2x80x9cGenistein Inhibition of the Growth of Human Breast Cancer Cells, Independence from Estrogen Receptors and the Multi-Drug Resistance Genexe2x80x9d by Peterson and Barnes, Biochemical and Biophysical Research, Communications, Vol. 179, No. 1, pp. 661-667, Aug. 30, 1991; xe2x80x9cGenistein and Biochanin A Inhibit the Growth of Human Prostrate Cancer Cells but not Epidermal Growth Factor Receptor Tyrosine Autophosphorylationxe2x80x9d by Peterson and Barnes, The Prostate, Vol. 22, pp. 335-345 (1993); and xe2x80x9cSoybeans Inhibit Manunary Tumors in Models of Breast Cancerxe2x80x9d by Barnes, et al., Mutagens and Carcinogens in the Diet, pp. 239-253 (1990).
As noted above, the aglucone isoflavones include daidzein, genistein, and glycitein. These aglucones have the following general formula: 
wherein, R1, R2, R3, R4 may be selected from the group consisting of H, OH and OCH3. Genistein has the formula above where R1=OH, R2=H, R3=OH, and R4=OH, daidzein has the formula above where R1=OH, R2=H, R3=H, and R4=OH, and glycitein has the formula above where R1=OH, R2=OCH3, R3=H, and R4=OH.
It is therefore to the aglucones and enrichment of a vegetable flour and a vegetable grit with these compounds to which the present invention is directed. The present invention is also directed to methods of making an aglucone enriched vegetable flour and an aglucone isoflavone enriched vegetable grit from a vegetable material containing isoflavone glucosides.
Processes are known in the art for converting isoflavone glucosides to aglucone isoflavones, such as described in Japanese Patent Application 258,669 to Obata, et al. These processes achieve only a moderate extent of conversion of the glucosides to aglucones, and require a substantial period of time to effect this moderate extent conversion. In addition, known processes such as described in the ""669 application are directed to removing the isoflavones from vegetable materials, and do not provide aglucone isoflavone enriched vegetable flour or grit products.
A process is also known for producing an aglucone isoflavone enriched vegetable protein fiber from a vegetable protein material, as described in U.S. Pat. No. 5,320,949 to Shen. The process is a process in which isoflavone glucosides in a vegetable fiber material are converted to aglucone isoflavones with a beta glucosidase enzyme.
An aglucone isoflavone enriched vegetable flour or grit and processes for producing the same are desirable, since production of commercial vegetable flours and grits is relatively inexpensive. An aglucone isoflavone enriched vegetable flour or grit, therefore, would be an inexpensive source of aglucone isoflavone enriched products.
It is therefore an object of the present invention to provide an aglucone isoflavone enriched vegetable flour and a process for producing the same from a vegetable material containing isoflavone glucosides.
It is further object of the present invention to provide an aglucone isoflavone enriched vegetable grit, and a process for producing the same from a vegetable material containing isoflavone glucosides.
In one aspect, the present invention is a process for producing an aglucone isoflavone enriched vegetable flour or grit from a vegetable material containing isoflavone glucosides. An aqueous slurry is formed of the vegetable material. An enzyme is contacted with the isoflavone glucosides in the slurry at a temperature and a pH for a time period sufficient to convert the isoflavone glucosides to aglucone isoflavones. The vegetable material is then comminuted to form an aglucone isoflavone enriched vegetable flour or grit.
In one embodiment, the enzyme is contacted with the isoflavone glucosides in the slurry at a temperature of about 5xc2x0 C. to about 75xc2x0 C. and a pH of about 3 to about 9. Preferably the enzyme is contacted with the isoflavone glucosides in the slurry for a period of about 1 to about 24 hours, most preferably for about 1 to about 3 hours, to convert at least a majority of the isoflavone glucosides to aglucone isoflavones.
In another embodiment of the invention, the enzyme is a supplemental enzyme which is added to the slurry in an amount effective to convert the isoflavone glucosides to aglucone isoflavones. Preferably, the supplemental enzyme is a saccharidase enzyme capable of cleaving 1,4-glucoside bonds. Most preferably, the supplemental enzyme converts substantially all of the isoflavone glucosides to aglucone isoflavones in about 1 hour to about 3 hours.
In a further aspect, the invention is a process for producing an aglucone isoflavone enriched vegetable flour or grit from a vegetable material containing isoflavone glucosides, where the vegetable material is initially comminuted to form a vegetable flour or grit. An aqueous slurry is formed of the vegetable flour or grit, and an enzyme is contacted with the isoflavone glucosides in the slurry at a temperature and a pH for a time period sufficient to convert the isoflavone glucosides to aglucone isoflavones. Preferably the enzyme is a supplemental enzyme contacted with the isoflavone glucosides in the slurry at about 5xc2x0 C. to about 75xc2x0 C. and at a pH of about 3 to about 9 for about 1 hour to about 24 hours. Most preferably the supplemental enzyme is a saccharidase enzyme capable of cleaving 1,4-glucoside bonds which is contacted with the isoflavone glucosides for a period of about 1 to 3 hours to convert substantially all of the isoflavone glucosides to aglucone isoflavones.
In still another aspect, the invention is a process for producing an aglucone isoflavone enriched soy flour or grit. A soy material containing isoflavone glucosides is provided from a group comprising soy cake, soy meal, soy chips, soy flakes, or combinations thereof. The isoflavone glucosides of the soy material are contacted with an enzyme at a temperature and a pH for a time period sufficient to convert the isoflavone glucosides to aglucone isoflavones. The soy material is comminuted to form an aglucone isoflavone enriched soy flour or grit.